/**
 *
 * htmlParser改造自: https://github.com/blowsie/Pure-JavaScript-HTML5-Parser
 *
 * author: Di (微信小程序开发工程师)
 * organization: WeAppDev(微信小程序开发论坛)(http://weappdev.com)
 *               垂直微信小程序开发交流社区
 *
 * github地址: https://github.com/icindy/wxParse
 *
 * for: 微信小程序富文本解析
 * detail : http://weappdev.com/t/wxparse-alpha0-1-html-markdown/184
 */
// Regular Expressions for parsing tags and attributes

const startTag = /^<([-A-Za-z0-9_]+)((?:\s+[a-zA-Z0-9_:][-a-zA-Z0-9_:.]*(?:\s*=\s*(?:(?:"[^"]*")|(?:'[^']*')|[^>\s]+))?)*)\s*(\/?)>/
const endTag = /^<\/([-A-Za-z0-9_]+)[^>]*>/
const attr = /([a-zA-Z0-9_:][-a-zA-Z0-9_:.]*)(?:\s*=\s*(?:(?:"((?:\\.|[^"])*)")|(?:'((?:\\.|[^'])*)')|([^>\s]+)))?/g

function makeMap(str) {
	const obj = {}
	const items = str.split(',')
	for (let i = 0; i < items.length; i += 1) obj[items[i]] = true
	return obj
}

// Empty Elements - HTML 5
const empty = makeMap('area,base,basefont,br,col,frame,hr,img,input,link,meta,param,embed,command,keygen,source,track,wbr')

// Block Elements - HTML 5
const block = makeMap('address,code,article,applet,aside,audio,blockquote,button,canvas,center,dd,del,dir,div,dl,dt,fieldset,figcaption,figure,footer,form,frameset,h1,h2,h3,h4,h5,h6,header,hgroup,hr,iframe,ins,isindex,li,map,menu,noframes,noscript,object,ol,output,p,pre,section,script,table,tbody,td,tfoot,th,thead,tr,ul,video')

// Inline Elements - HTML 5
const inline = makeMap('a,abbr,acronym,applet,b,basefont,bdo,big,br,button,cite,del,dfn,em,font,i,iframe,img,input,ins,kbd,label,map,object,q,s,samp,script,select,small,span,strike,strong,sub,sup,textarea,tt,u,var')

// Elements that you can, intentionally, leave open
// (and which close themselves)
const closeSelf = makeMap('colgroup,dd,dt,li,options,p,td,tfoot,th,thead,tr')

// Attributes that have their values filled in disabled="disabled"
const fillAttrs = makeMap('checked,compact,declare,defer,disabled,ismap,multiple,nohref,noresize,noshade,nowrap,readonly,selected')

function HTMLParser(html, handler) {
	let index
	let chars
	let match
	let last = html
	const stack = []

	stack.last = () => stack[stack.length - 1]

	function parseEndTag(tag, tagName) {
		// If no tag name is provided, clean shop
		let pos
		if (!tagName) {
			pos = 0
		} else {
			// Find the closest opened tag of the same type
			tagName = tagName.toLowerCase()
			for (pos = stack.length - 1; pos >= 0; pos -= 1) {
				if (stack[pos] === tagName) break
			}
		}
		if (pos >= 0) {
			// Close all the open elements, up the stack
			for (let i = stack.length - 1; i >= pos; i -= 1) {
				if (handler.end) handler.end(stack[i])
			}

			// Remove the open elements from the stack
			stack.length = pos
		}
	}

	function parseStartTag(tag, tagName, rest, unary) {
		tagName = tagName.toLowerCase()

		if (block[tagName]) {
			while (stack.last() && inline[stack.last()]) {
				parseEndTag('', stack.last())
			}
		}

		if (closeSelf[tagName] && stack.last() === tagName) {
			parseEndTag('', tagName)
		}

		unary = empty[tagName] || !!unary

		if (!unary) stack.push(tagName)

		if (handler.start) {
			const attrs = []

			rest.replace(attr, function genAttr(matches, name) {
				const value = arguments[2] || arguments[3] || arguments[4] || (fillAttrs[name] ? name : '')

				attrs.push({
					name,
					value,
					escaped: value.replace(/(^|[^\\])"/g, '$1\\"') // "
				})
			})

			if (handler.start) {
				handler.start(tagName, attrs, unary)
			}
		}
	}

	while (html) {
		chars = true

		if (html.indexOf('</') === 0) {
			match = html.match(endTag)

			if (match) {
				html = html.substring(match[0].length)
				match[0].replace(endTag, parseEndTag)
				chars = false
			}

			// start tag
		} else if (html.indexOf('<') === 0) {
			match = html.match(startTag)

			if (match) {
				html = html.substring(match[0].length)
				match[0].replace(startTag, parseStartTag)
				chars = false
			}
		}

		if (chars) {
			index = html.indexOf('<')
			let text = ''
			while (index === 0) {
				text += '<'
				html = html.substring(1)
				index = html.indexOf('<')
			}
			text += index < 0 ? html : html.substring(0, index)
			html = index < 0 ? '' : html.substring(index)

			if (handler.chars) handler.chars(text)
		}

		if (html === last) throw new Error(`Parse Error: ${html}`)
		last = html
	}

	// Clean up any remaining tags
	parseEndTag()
}

export default HTMLParser
